1. Field of Invention
The present invention relates to a manufacturing and quality controlling method of optical sheets. More particularly, the present invention relates to an apparatus and method for automatically measuring a curl of an optical sheet in real time.
2. Description of Related Art
A liquid crystal display (LCD) has many advantages over conventional types of displays having high display quality, small volume, low driving voltage and low power consumption and being lightweight. Hence, LCDs are widely used in small portable televisions, mobile telephones, video recording units, notebook computers, desktop monitors, projector televisions and so on, and have gradually replaced the conventional cathode ray tube (CRT) as a mainstream display unit.
Polarizers are main components of a liquid crystal panel in a liquid crystal display. A polarizer can be composed of one or more optical sheets, and in addition to the polarizing function can have other functions, such as anti-peeping or optical compensation. An optical sheet may have a curl due to bad manufacturing. The curled optical sheet cannot be adhered smoothly onto the liquid crystal panel and therefore causes the liquid crystal display to have bad quality.
The prior art usually manually measures curls of optical sheets after manufacturing the optical sheets to select good optical sheets, which meet the quality control level regarding curls. However, the conventional method of manual measurement is not convenient and is also inaccurate, and thus easily causes poor quality control due to measurement errors. Moreover, manual measurement takes a long time, slows the manufacturing rate, wastes manpower and thus increases manufacturing costs.